Roll out furnace grate

ABSTRACT

The grate is supported in raised, operative position by a raising and lowering mechanism. For cleaning, the grate is lowered onto track rails in an air chamber below the grate. By opening a door in the furnace air jacket the grate may be pulled out onto exterior track rails for cleaning. The grate is equipped with a water cooling coil and flexible hose connections which accommodate travel of the grate into and out of the furnace without disconnection of the water supply. When the grate is pulled out of the furnace it disengages from the raising and lowering mechanism and when rolled back into the furnace it reengages with the raising and lowering mechanism and is lifted to operative position. Instead of cleaning the grate immediately and returning it to the furnace, it may be replaced with a cleaned grate in order to get the furnace back into operation more quickly.

United States Patent Jones [54] ROLL OUT FURNACE GRATE Allen J. Jones, Fall Creek, Oreg.

Michel Lumber Company, Lake Oswego, Oreg.

[22] Filed: Nov. 9, 1970 [21] Appl. No.: 87,806

[72] Inventor:

[ 73] Assignee:

[52] [1.5. CI ..l22/374, 1 10/88 [51] Int. Cl ..F23h 3/04 [58] Field of Search ..122/374; 110/45, 88, 89

[56] I References Cited UNITED STATES PATENTS [451 May 30,1972

Primary ExaminerKenneth W. Sprague Attomey-Lee R. Schermerhom [5 7] ABSTRACT The grate is supported in raised, operative position by a raising and lowering mechanism. For cleaning, the grate is lowered onto track rails in an air chamber below the grate. By opening a door in the furnace air jacket the grate may be pulled out onto exterior track rails for cleaning. The grate is equipped with a water cooling coil and flexible hose connections which accommodate travel of the grate into and out of the furnace without disconnection of the water supply. When the grate is pulled out of the furnace it disengages from the raising and lowering mechanism and when rolled back into the furnace it reengages with the raising and lowering mechanism and is lifted to operative position. instead of cleaning the grate immediately and returning it to the furnace, it may be replaced with a cleaned grate in order to get the furnace back into operation more quickly.

Patented May 30, 1972 2 Sheets-Sheet l I/VVENTOR ALLEN J. JONES T2 0 Patented May 30, 1972 3,665,894

2 Sheets-Sheet 2 w j, INVENTOR ALLEN J. JONES BACKGROUND OF THE INVENTION This invention relates to a furnace grate which is arranged to be moved out of the furnace for cleaning from time to time.

In furnaces for certain purposes, such as heating wood veneer driers, it is desirable to use wood waste products heretofore considered as refuse, as fuel for the furnace. This not only provides a very economical source of fuel but also solves the problem of disposal of various types of wood refuse which accumulate in great quantities in sawmills, veneer and plywood plants and the like. Some of this refuse, such as bark for example, contains a large amount of non-combustible material which accumulates on the grate and makes frequent cleaning of the grate necessary. .It is desired to provide grates for burning such material which may be cleaned from time to time without taking the furnace out of operation for more than a very brief interval.

Objects of the invention are therefore, to provide a furnace grate which may be easily and quickly removed for cleaning and then replaced without prolonged loss of heat from the furnace, to provide a grate which will successfully burn wood refuse products having a high' content of non-combustible material, to provide a water cooled grate which may be rolled out of a furnace on a track for cleaning without disconnecting the water supply, and to provide a mechanism by which a grate may be conveniently removed from a furnace and replaced by a clean grate.

SUMMARY OF THE INVENTION Inthe present construction the grate is supported in operative position by at raising and lowering mechanism which is arranged to lower the grate onto track rails at the bottom of an air chamber below the grate. Then, by opening a door in the air jacket of the furnace, the grate may be pulled out onto exterior track rails for cleaning or replacement by an already cleaned grate. Thegrate has flexible cooling water connections which accommodate the travel of the grate on the interior and exterior tracks. When the grate is pulled out of the furnace it disengages itself from the raising and lowering mechanism and when the grate is pushed back into the furnace it reengages so that it may be raised into operative position with a minimum loss of time.

When it is time to clean the grate, the fuel may be burned down to a minimum and the grate cleaned and replaced while the furnace temperature remains high enough for re-ignition of new fuel without resorting to kindling or auxiliary fuel. The system also facilitates inspection and repair of the grate when necessary. Simple repairs or replacement may be accomplished in a matter of minutes thereby avoiding shutdown of furnace operation.

The invention will be better. understood and additional objects and advantages will become apparent from the following description of the preferred embodiment illustrated in the accompanyingdrawings. Various changes may be made in details of construction and arrangement of parts and certain features may be used. without others. All such modifications within the scope of the appended claims are included in the invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical sectional view, with parts broken away, showing the lower part of a furnace equipped with a grate embodying the invention, the grate being shown in full lines in lowered position ready to be rolled out of the furnace and shown in broken lines in operative position and cleaning position;

FIG. 2 is a view of the grate on the line 2-2 in FIG. 1, with parts broken away;

FIG. 3 is a front elevation view of the lower part of the furnace, with parts broken away, showing the grate in operative position; and v FIG. 4 is an isometric view of the grate raising and lowering mechanism.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1 a cylindrical refractory wall I defines a combustion zone 11 above the grate unit 12 which is shown in operative position in broken lines at 12a. In its operative position the grate unit is held up against the lower edge of a stationary, cylindrical, vertical grate 13 which abuts the lower end of refractory wall 10. Stationary grate 13 is equipped with a water cooling coil 14. Wall and vertical grate 13, which forms a continuation of wall 10, are provided with tuyeres 15 and 16.

A rectangular sheet metal air jacket encloses the parts just described. Air jacket 20 is equipped with an upper support plate 21 for the refractory wall 10 and a lower support plate 22 for the vertical grate 13. These support plates also form air zone separators defining an air zone 23 to supply the tuyeres 15, an air zone 24 to supply the tuyeres 16 and an air zone 25 under the grate unit when the latter is in operative position at 12a. Thus, the air pressures may be controlled as desired in the three zones 23, 24 and 25 to promote the most efficient combustion of the type of fuel being used.

- Grate unit 12 comprises a support plate which is apertured at 31, a water cooling coil 32 and the grate 33 which is apertured at 34. Apertures 31 and 34 convey air from the bottom air zone 25 up through the bed of fuel on grate 33 to assist in combustion. The fuel is dropped onto the grate by gravity by a suitable feed means, not shown, in an upper portion of refractory wall 10. After a number of hours of operation with wood refuse fuel as previously mentioned, a layer 35 of ash and non-combustible materials accumulates on grate 33 necessitating cleaning of the grate to restore proper air circulation through the grate apertures 31 and 34.

Grate support plate 30 is mounted on wheels 40 arranged to roll on a pair of interior track rails 41 at the bottom of air zone 25. An airtight clean out door 42 is mounted on a piano hinge 43 at the bottom of the front wall of air jacket 20 so as to swing down to horizontal position as shown in FIG. 1. A pair of exterior track rails 45 is mounted on hinges 46 in front of the furnace to swing down on top of the open door 42 in alignment with the interior track rails 41. When not in use, the exterior track rails 45 may be swung up to vertical position at 45a allowing door 42 to be closed.

Flexible inlet and outlet water supply hoses 47 and 48 on the'cooling coil 32 allow the grate unit to be manually pulled out on exterior track 45 to its position indicated at 12b for cleaning or replacement. The upper edge of door 42, is notched to fit around the protruding ends of cooling coil 32. If it is not desired to clean the grate immediately, the grate unit may be lifted ofi track 45 by a lift truck or chain hoist and set aside for cleaning or repair while a cleaned grate unit is replaced on track 45 and hose connections 47, 48 transferred to the new grate unit. I

Alternatively, the track rails 41 and 45 may be equipped with rollers and the grate unit 12 equipped with runners to ride on the track rollers.

Grate unit 12 includes a pair of horizontal bars 50 for raising the unit to its operative position at 12a. When the grate unit is pushed back into the furnace on interior rails 41, the left ends of bars 50 enter a pair of rings 51 on the lower ends of a pair of back lifting links 52. As the bars 50 enter the rings 51, the inward movement of the grate unit is arrested by engagement of a bumper 53 on support plate 30 with a stationary vertical stop 54.

At the same time, the nose ends 55 on a pair of vertical hooks 56 on the front ends of grate bars 50 enter openings or rings 59 in the lower ends of a pair of front lifting links 60. See FIGS. 3 and 4. Links 52 and 60 extend downward through small openings 61 in support plate 21 and large openings 62 in support plate 22 for lifting grate unit 12 up to its operative position at 12a. The back links 52 are equipped with small air seal plates 63 which pass through openings 62 and close the small openings 61. Larger air seal plates 64 on the links 52 close the large openings 62. Hooks 56 are similarly provided with small air sea] plates 65 to close the small openings 61 and large air sea] plates 66 to close the large openings 62.

The lifting links 52 and 60 are each made in two parts to provide a length adjustment at 69. The upper ends of links 52 are pivotally connected to a pair of lifting arms 70 and the upper ends of links 60 are pivotally connected to a pair of lifting arms 71. Arms 70 are fixedly mounted on a horizontal shaft 75 and arms 71 are fixedly mounted on a horizontal shaft 76 as shown in FIG. 4. These shafts are mounted for rotation in suitable bearings 77 in air jacket 20.

Shafts 75 and 76 project through a side wall of air jacket 20 and have operating arms 80 and 81 on the outside of the air jacket. The ends of arms 80 and 81 are interconnected by an equalizing cable 82 which passes through a pulley block 83. Pulley block 83 is suspended on the end of a cable 84 which may be raised and lowered by a winch unit 85 on the outside of air jacket 20. Thus, the raising and lowering mechanism is isolated from the heat of combustion zone 11.

The parts are shown in raised position in full lines in FIG. 4, which places the grate unit in its operative position indicated at 12a in FIG. 1. The lower and upper grate unit positions 12 and 12a are represented by phantom lines in FIG. 4. When pulley block 83 is lowered by winch unit 85, the arms 80 and 81 and the shafts 75 and 76 rotate approximately 90 to place the parts in position shown in broken lines in FIG. 4 with wheels 40 resting on interior track rails 41 in FIG. 1.

Then door 42 is opened and outside track rails 45a lowered on top of the door as previously described. When the grate unit is pulled out in the direction of arrow 90 in FIG. 4, the nose ends 55 of front hooks 56 disengage themselves from rings 59 in front links 60 and the back ends of bars 50 disengage themselves from lifting rings 51. When a cleaned grate is pushed into the furnace on track rails 41, these parts reengage as previously described and reverse operation of winch unit 85 raises the pulley block 83 to lift the grate unit to its operative position at 12a. Equalizing cable 82 causes both front and back portions of the bottom grate unit 12 to be pulled up snugly against the lower edge of stationary vertical grate 13.

Having now described my invention and in what manner the same may be used, what I claim as new and desire to protect by Letters Patent is:

1. A furnace comprising a refractory wall enclosing a combustion chamber, an air jacket surrounding said refractory wall, a clean out door in said air jacket, an interior track within said air jacket terminating at said door, an exterior track outside of said air jacket aligned with said interior track, a grate, lifting means disposed between said refractory wall and said air jacket arranged to lower said grate onto said interior track and raise said grate from said track to operative position at the bottom of said combustion chamber, and interengaging parts on said grate and lifting means arranged to disengage from each other by movement of the grate out of the furnace on said tracks and reengage with each other by movement of the grate into the furnace on said tracks.

2. A furnace as defined in claim 1, said interengaging pans comprising rings and members relatively movable into and out of said rings by said inward and outward movements of said grate on said tracks.

3. A furnace as defined in claim 2 including front and back lifting links on said lifting means having said rings, said members movable into and out of said rings being on the front and back ends of said grate.

4. A furnace as defined in claim 3 including horizontal bars in said grate parallel with said track, said members movable into said rings on said back lifting links comprising the back ends of said bars, and said members movable into said rings on said front lifting links comprising hooks on the front ends of said bars.

5. A furnace as defined in claim 3 including front and back horizontal shafis having arms in said air jacket connected with said front and back lifting links, said shafts extending through said air jacket, and power operated means outside of said air jacket arranged to rotate said shafts.

6. A furnace as defined in claim 5, said power operated means comprising a pair of arms on said shafts, an equalizing cable interconnecting said arms, a pulley block receiving a mid portion of said cable, a winch cable connected with said pulley block, and a winch arranged to raise and lower said winch cable and pulley block.

7. A furnace as defined in claim 1 including means for pivotally mounting said exterior track allowing the exterior track to swing to upright position when not in use.

8. A furnace as defined in claim 1 including a water cooling coil in said grate, and flexible hose connections on said coil to accommodate movements of said grate. 

1. A furnace comprising a refractory wall enclosing a combustion chamber, an air jacket surrounding said refractory wall, a clean out door in said aIr jacket, an interior track within said air jacket terminating at said door, an exterior track outside of said air jacket aligned with said interior track, a grate, lifting means disposed between said refractory wall and said air jacket arranged to lower said grate onto said interior track and raise said grate from said track to operative position at the bottom of said combustion chamber, and interengaging parts on said grate and lifting means arranged to disengage from each other by movement of the grate out of the furnace on said tracks and reengage with each other by movement of the grate into the furnace on said tracks.
 2. A furnace as defined in claim 1, said interengaging parts comprising rings and members relatively movable into and out of said rings by said inward and outward movements of said grate on said tracks.
 3. A furnace as defined in claim 2 including front and back lifting links on said lifting means having said rings, said members movable into and out of said rings being on the front and back ends of said grate.
 4. A furnace as defined in claim 3 including horizontal bars in said grate parallel with said track, said members movable into said rings on said back lifting links comprising the back ends of said bars, and said members movable into said rings on said front lifting links comprising hooks on the front ends of said bars.
 5. A furnace as defined in claim 3 including front and back horizontal shafts having arms in said air jacket connected with said front and back lifting links, said shafts extending through said air jacket, and power operated means outside of said air jacket arranged to rotate said shafts.
 6. A furnace as defined in claim 5, said power operated means comprising a pair of arms on said shafts, an equalizing cable interconnecting said arms, a pulley block receiving a mid portion of said cable, a winch cable connected with said pulley block, and a winch arranged to raise and lower said winch cable and pulley block.
 7. A furnace as defined in claim 1 including means for pivotally mounting said exterior track allowing the exterior track to swing to upright position when not in use.
 8. A furnace as defined in claim 1 including a water cooling coil in said grate, and flexible hose connections on said coil to accommodate movements of said grate. 